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    I wondered if you could tell me the number of aromatic and carbon environments in EthylBenzene (which I think has molecular formula C8H10).

    I think it has 5 carbon environments and 3 aromatic environments but my book seems to say it has 1 more of each so 6 carbon environments and 4 aromatic environments?

    I have circled each carbon environment with a different colour for different environments which I think are correct, also my book seems to think the skeletal formula I have drawn in the picture has molecular formula C8H8 and I'm just wondering if it does? If it isn't a typo then I'm missing out something....




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    (Original post by Sekonda)
    I wondered if you could tell me the number of aromatic and carbon environments in EthylBenzene (which I think has molecular formula C8H10).

    I think it has 5 carbon environments and 3 aromatic environments but my book seems to say it has 1 more of each so 6 carbon environments and 4 aromatic environments?

    I have circled each carbon environment with a different colour for different environments which I think are correct, also my book seems to think the skeletal formula I have drawn in the picture has molecular formula C8H8 and I'm just wondering if it does? If it isn't a typo then I'm missing out something....




    Thanks.
    yep...that looks right and i got the formula c8h10
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    It's good to have reassurance, thanks!
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    (Original post by Sekonda)
    I wondered if you could tell me the number of aromatic and carbon environments in EthylBenzene (which I think has molecular formula C8H10).

    I think it has 5 carbon environments and 3 aromatic environments but my book seems to say it has 1 more of each so 6 carbon environments and 4 aromatic environments?

    I have circled each carbon environment with a different colour for different environments which I think are correct, also my book seems to think the skeletal formula I have drawn in the picture has molecular formula C8H8 and I'm just wondering if it does? If it isn't a typo then I'm missing out something....




    Thanks.
    There are six carbon environments and three aromatic environments, the reason being that the last threed red ones are not similar - the one in the middle is influenced by its neighbours that are in turn influenced by their neighbours, etc. Its carbon 4 I am talking about (but check with someone else, just in case)
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    There are actually 5 proton environments overall, with 3 being aromatic and 2 aliphatic. The one you have circled green will not have any peak in the 1H-NMR spectrum because there is no proton there. Remember that substituted positions on a benzene ring never have a proton on them as the carbon would have 5 bond then (not allowed). As for the aromatic protons, the ones in the 2 and 6 positions (circled blue) are equivalent by symmetry, as are positions 3 and 5, and position 4 is the final environment. If you're not convinced they're the same by symmetry then remember that the ethyl group has free rotation around its C-C single bonds. This rotation is faster than the time the NMR machine can take a reading, so the rest of the aromatic protons won't know what way it's pointing. The two environments on the ethyl branch will be very distinct, but the chemical shifts on the aromatic protons have very similar chemical shifts so you'll get a bit of a mess on the spectrum, which is found here: http://www.sigmaaldrich.com/spectra/fnmr/FNMR010362.PDF

    EDIT: Sorry, I just realised you already got the question right and it's your book that said 6 environments with 4 aromatic ones. So yes, essentially the book is wrong and you are right.
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    (Original post by AutVinceriAutMori)
    There are six carbon environments and three aromatic environments, the reason being that the last threed red ones are not similar - the one in the middle is influenced by its neighbours that are in turn influenced by their neighbours, etc. Its carbon 4 I am talking about (but check with someone else, just in case)
    I think there are six carbon env..
    This thread is so confusing ..would be gud if somebody put the final answer in the last post
 
 
 
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